ALMA Special Session AAS 243

243rd American Astronomical Meeting - New Orleans Convention Center | New Orleans, Louisiana | January 7-11, 2024

ALMA as a high-z powerhouse: the impact of the Wideband Sensitivity Upgrade

The NAASC will host a special session at the upcoming Winter AAS Meeting in New Orleans, held on Monday January 8, 2024, 10am to 11:30am (Central Time). This special session will present high-profile results obtained through ALMA programs in different areas of high-z studies – including large programs, current and expected synergies with high-sensitivity facilities, and the expected yield from ALMA observations after different phases of the Wideband Sensitivity Upgrade (WSU)are achieved. The session will include 4 invited talks by J. Yang (U. Arizona), A. Long (UT Austin), J. Spilker (Texas A&M) and D. Burgarella (LAM Marseille), and a short general presentation of the WSU.

Abstract:

In recent years, the use of ALMA for the characterization of high-z sources (galaxies, AGNs and quasars) has considerably expanded beyond the initial goal to detect molecular emission in Milky Way analogs at z = 3. ALMA will soon acquire a new and transformational role in the field with the implementation of the ongoing Wideband Sensitivity Upgrade (WSU), which will upgrade ALMA’s digital path, correlator, and the first three wideband receivers by the end of this decade, with additional receiver bands to follow. The current impact of ALMA is demonstrated by an increasing number of high-profile publications on sources at z 2~9 on questions as diverse as AGN jets kinematics, lensed dusty galaxy surveys, molecular composition of the cold gas component of SFGs, and the establishment of precise spectroscopic redshifts using atomic and ionized lines of C and O. The recent installation of the new ALMA Band 1 (35-50 GHz) also opened the ability to search for redshifted low-J CO lines, which are a good diagnostic for estimating the mass of the molecular gas reservoir. Considering the significant discovery space in this domain to be opened by current and future facilities – JWST and Roman in particular - ALMA will leverage the expected trove of high-z detections by providing for a significant number of these sources the baseline physical context to understand AGN accretion and galaxy evolution across cosmic times. The WSU, in addition to allowing much more efficient spectral scanning for redshift surveys, will provide dramatically improved sensitivity across the board (line sensitivity by a factor ~1.5, continuum sensitivity by a factor ~1.6-2) directly translating into deeper and more efficient detections.

Schedule: https://submissions.mirasmart.com/AAS243/Itinerary/EventDetail.aspx?evt=62

Presentations titles and abstracts

J. Spilker: Cleaning up the high-redshift dusty universe with JWST and Wideband ALMA PDF presentation

The first generation of massive galaxies assembled very rapidly, with star formation rates hundreds or thousands of times higher than the Milky Way. This star formation was almost entirely obscured by dust, making such galaxies nearly invisible even in deep Hubble imaging but bright at the submillimeter wavelengths accessible by ALMA. JWST's rest-optical wavelength coverage and exquisite sensitivity, paired with the wide bandwidth of a suite of upgraded ALMA receivers, offer qualitatively new views into the formation and evolution of the most dust-obscured galaxies at high redshift. I will present some early results that pair JWST with current-generation ALMA data to resolve the structure, feeding, and feedback in and around a few well-studied lensed dusty galaxies.  

A. Long:  ALMA & Massive Galaxy Evolution in the First 2 Billion Years

One of the most puzzling discoveries of the decade is that substantial populations of massive galaxies ceased forming stars as early as two billion years after the Big Bang (i.e. by z = 3). These are likely some of the first galaxies in the Universe, yet we still do not understand how they form and evolve so rapidly. In order to piece the evolutionary puzzle together, we must capture large samples of massive galaxies at all phases of their evolution, from gas-rich star formers to fully quiescent systems -- all at z > 3. Due to the rarity and diversity of the massive galaxy population at z > 3, such an endeavor requires a combination of wide-field observations from the UV to millimeter. I will present new results on z > 3 DSFGs identified in the Ex-MORA survey -- the largest ever ALMA blank-field survey -- which is specifically designed to capture massive z > 3 galaxies too dust obscured to be detected in most pre-JWST UV/optical surveys. I will also highlight current efforts that combine incoming JWST and ALMA observations to discover and characterize z > 3 massive post-starburst and quiescent galaxies in the same field. Finally, I will explain how all of these efforts will be immensely improved by the ALMA Wideband Sensitivity Upgrade.

J. Yang: Probing co-evolution between the earliest supermassive black holes and host galaxies using JWST and ALMA PDF presentation

High-redshift quasars are unique probes for investigating the growth of the earliest supermassive black holes (SMBHs), the assembly of their massive host galaxies, and the co-evolution between the two. However, it has been challenging to place tight constraints on the connection between central SMBHs and host galaxies in high-redshift quasars, due to limitations in observations. Now, the combination of JWST and ALMA is opening up a new era. I will present some new results from observations of luminous quasars at z>6.5 using JWST and ALMA. Based on several JWST and ALMA programs, we have constructed a sample of ~ 30 luminous quasars at z~6.5-7.6, covered by both JWST and ALMA observations. Particularly, half of them have both high spatial resolution (~0.1 arcsec) JWST and ALMA observations. These quasars have JWST spectroscopic observations of the rest-frame optical emission, which enables us to obtain reliable measurements of their virial BH mass and to characterize quasar physics. We are also able to carry out a first search for AGN feedback via [OIII] in high-redshift quasars. With JWST images, we can for the first time separate the stellar light of host galaxies from the bright central point sources, to uncover the diverse quasar hosts in the early Universe. The first results have revealed extended emission from the host galaxies, galactic-scale outflows, and close companion galaxies. The ALMA observations provide deep insights into the morphology and gas kinematics of these quasar host galaxies in the rest-frame far-infrared in great detail. The high-resolution [CII] observations at 0.1 arcsec reveal complex quasar host galaxies and quasar-companion systems. The combined JWST-ALMA dataset offers a comprehensive suite of dust, gas, and stellar light observations for these most distant quasar-hosts, providing complete measurements of BH mass, dynamical mass, and stellar mass.

Denis Burgarella: ALMA's perspective on the Universe at the Epoch of Reionization

ALMA provides astronomers with the most sensitive and best angular resolution in the sub-millimeter and millimeter ranges. These characteristics are necessary to study the Universe at high, and ultra-high redshifts. The information collected by ALMA on these objects is fundamental because it allows to study the interstellar medium in the very first phases of galaxy evolution. More specifically, ALMA brings a unique information on the dust emission. For galaxies at z > 4-6, this is the only way to probe the formation of the first dust grains in the Universe. Through the far-IR fine-structure lines, ALMA also permits to constrain the gas characteristics in the HII regions (mainly [OIII] line) and in the photodissociation regions (mainly [CII] line). Beyond this physical information, ALMA observations are necessary to better estimate photometric redshifts through SED fitting, and to estimate spectroscopic redshifts via the emission lines. However, the present ALMA is still limited and we can hardly study large galaxy samples in the early Universe.
With the implementation of the ongoing Wideband Sensitivity Upgrade (WSU), ALMA’s efficiency to estimate redshifts will be improved. The better sensitivity (line sensitivity by a factor ~1.5, continuum sensitivity by a factor ~1.6-2) and mapping speed (2x - 5x) are also necessary to reach out the most distant objects. We expect a strong impact on the scientific outcome that is very necessary with the advent of JWST that opened up the z > 9 Universe to physical analysis, and with the future facilities (ELT, Roman Space Telescope, SKA).